Pregnant women warned paracetamol may lower testosterone production in unborn boys

Researchers at the Medical Research Council (MRC) Centre at the University of Edinburgh are saying that prolonged use of paracetamol during pregnancy may reduce testosterone production in unborn boys. Paracetamol is the primary drug recommended to pregnant women for treating pain and fever.

It is thought that this research could help explain links between paracetamol use in pregnancy and reproductive health issues in young boys. Testosterone is critical for life-long male health and reduced exposure to the hormone in the womb has been connected with increased infertility, testicular cancer and undescended testicles. The authors advise that expectant mothers follow existing guidelines and take the lowest effective dose for the shortest possible time.

The study examining the effect of paracetamol on testosterone was conducted on mice carrying skin grafts of human testicular tissue. These grafts are said to mimic how the testes develop during pregnancy. These mice were given a typical daily dose of paracetamol over 24 hours or seven days. The amount of testosterone produced was measured one hour after the final dose was administered.

No effect on testosterone production was reported after 24 hours, however it reduced by a very significant 45% after seven days. The team say further research is needed to establish the mechanism by which paracetamol might be responsible for this reduction in testosterone.